1. Technical Field
This invention relates to measuring devices and relates in particular to a combination device useful to measure length of flexible line moved through the device and any tensile force in the line.
2. Background Information
A number of measuring devices are known for use with flexible line reels and wireline units for various well servicing operations in the petroleum industry. Many well servicing operations involve lowering well tools into a well flow conduit and retrieving them from the conduit on flexible line. The flexible line usually used is metal cable or solid metal "wireline", which is wound on and off a drum by a reeling device. A number of devices are available which measure length of line wound off a reeling device to indicate depth the tool has been lowered into the well conduit. Some of these measurement devices also indicate tensile force in the line from weight of line and well tools suspended in the conduit.
A "standard measuring device" is shown and described on page 2584 of the "Composite Catalog of Oil Field Equipment and Services", 37th revision, Volume 2, published by World Oil.RTM., Box 2608, Houston, TX 77001. This measuring device has long been used extensively throughout the petroleum industry for measuring length of line moved through the device only. Use of this device contributes to early fatigue failure from bending of steel "measuring line" as the line is bent from straight 360.degree. or one complete wrap around the measuring wheel and back to straight as line moves through the device.
An example of a "measuring head", which also measures length of line moved through only, is shown on page 3.2 of "SIE Wireline Products", a publication of SIE, 7450 Winscott Rd., Ft. Worth, Texas 76126.
An example of a measuring device, which measures line tension and is supplied with a "live shaft" to which a counter may be connected, is shown on page 13 of Martin-Decker 1988-89 Catalog, published by Martin-Decker, 1200 Cypress Creek Rd., Cedar Park, Tex. 78613.
Shown on page 21 of a publication entitled "Mathey Wireline Units", by Mathey International, Ltd., P.O. Box 472110, Tulsa, OK 74147, are a number of "Depth Measuring Units" which measure length of line moved through the unit only. Also shown on page 21 are combination measuring units, which measure both length of line and "weight on" (tensile force in) the line.
"S.S.R. International Sales Catalogue Issue 4" also shows "counterheads" without load cells (for length measurement only) and a number of types of "counterheads" with load cells (for measurement of length and tensile force in the flexible line). This catalog was published by S.S.R. (International) Limited, Dyce, Aberdeen AB2 OGA, U.K.